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In this paper a novel multi-functional composite with high electrical conductivity and excellent magnetic field sensitivity was fabricated by embedding carbon nanotubes (CNTs) and carbonyl iron powders (CIPs) into shear-stiffening gel (STG). Oscillatory shear test demonstrated its excellent rheological properties. When the mass fractions of CNTs and CIPs were 1 wt% and 50 wt%, the increase in storage modulus (G′) reached 585% under 100 Hz oscillatory shear and 428% under 1.2 T magnetic flux density with respect to its initial state. The resistivity of this CNT-CIP-STG composite achieved 25 Ω m and showed strong dependence on the magnetic field. When the external magnetic flux density was 873 mT, the normalized electrical resistance response reached up to − 40.5%. Linearly increasing and step magnetic field was employed to study the electrical and mechanical behaviors of this CNT-CIP-STG composite. The instantaneous response and time effect were discussed. Interestingly, oscillatory shear showed limited influence on the electrical conductivity but notable enhancement on the sensitivity to magnetic field. A mechanic-electric coupling mechanism was proposed to illustrate enhancement of shear thickening effect and sensibility to magnetic field. [ABSTRACT FROM AUTHOR]

The present paper deals with postbuckling characteristics of carbon nanotube reinforced composite (CNTRC) rectangular plates with integrated piezoelectric layers subjected to in-plane compressive loads. The von Karman type of geometrical nonlinearity is taken into consideration to account for the large deformations of the plate. The dispersion of CNTs may be uniform or functionally graded and the distribution of electric potential across the thickness of piezoelectric layers is simulated by a combination of linear and sinusoidal functions. Generalized differential quadrature method is employed to discretize nonlinear stability equations, boundary conditions and Maxwell equation and then nonlinear system of equations is solved using a displacement control strategy. A comprehensive parametric study is presented to provide an insight into effects of CNT dispersion and volume fraction, geometrical parameters, type of in-plane load, boundary conditions, thickness of piezoelectric layers and external applied voltages on the postbuckling behaviors of the nanocomposite plate. It is shown that snap-through type of instability, which is known as secondary instability, occurs during postbuckling regime. It is revealed that both volume fraction and dispersion of the CNTs could affect the snap-through characteristics of the plate. It is found that snap-through instability is sensitive to thickness of the piezoelectric layers. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET) composites were loaded with four different carbon-based fillers: functionalized carbon nanotubes (CNT), exfoliated graphite (EG), and hybrid materials such as Mg(OH) 2 , which is primarily used as a flame retardant additive in plastics, dispersed over functionalized CNT and EG. The technology used to mix the different phases was high energy ball milling in dry conditions and at ambient temperature. Morphological organization, thermal and electrical properties of composites were evaluated and correlated with the type of filler. The electrical properties were analyzed over a wide temperature range, from 25 °C to 150 °C, and correlated to the starting structural organization of the composites and the morphological transformations occurred during the thermal heating. The addition of EG and CNTs to PET did not have influence on the amorphous arrangement of unfilled PET, while the loading of Mg(OH) 2 /EG and Mg(OH) 2 /CNT fillers favoured the PET crystallization. The crystallization inducted by temperature allowed an increasing in electrical conductivity of the starting amorphous samples. On the other hand, it was found a conductivity independent of temperature for semicrystalline samples (filled with Mg(OH) 2 /EG and Mg(OH) 2 /CNT). The charge transport, for the analyzed PET composites, is favoured by the higher degree of crystallinity. [ABSTRACT FROM AUTHOR]

The ability to control the dispersion state of carbon nanotubes (CNTs) in polymer matrices is closely related to the electrical tunability of polymer-CNT nanocomposites. In this study, the effect of polymer-CNT interactions at the molecular level on the extent of CNT dispersion and consequent electrical properties of the developed nanocomposites are investigated. Two polymer models with dissimilar affinities towards CNTs are studied: polyamide-6 (PA6) having high, and polystyrene (PS) having low affinity towards CNTs. Experiments demonstrate that enhanced polymer-filler interactions in PA6-CNT system lead to improved CNT dispersion at the nanoscopic level. However, PS-CNT system, having higher number density of micro-agglomerates, has approximately ten times lower percolation threshold (0.3 wt% versus 2.9 wt%) and significantly enhanced electrical properties. High affinity of PA6 towards CNTs is proposed to adversely influence electrical properties via encapsulation of CNTs by PA6 through possible wrapping and interfacial crystallization of polymer chains. On the other hand, enhanced electrical properties in PS-CNT nanocomposites are attributed to higher number density of micro-agglomerates, contributing to secondary internal electric field. [ABSTRACT FROM AUTHOR]

This article describes nanocomposites of triblock copolymer styrene–ethylene/butylene–styrene doping with 5 wt% of multiwalled carbon nanotubes (CNTs) prepared by melt mixing process. The selection of processing temperature was made according to the state of macrodispersion of CNTs within polymer matrix. Afterwards, the relationship between rotational speed, mixing time and electrical conductivity has been noted. It was confirmed that the temperature of 300°C and rotational speed of 100 r/min lead to significant decreasing of CNT agglomerations resulting in high electrical conductivity equal to 8.0 S/m. [ABSTRACT FROM AUTHOR]

We report a large reduction in contact resistance between stretchable carbon nanotube/silicone rubber composites and silver electrodes by a chemical surface treatment, accompanied by an enhancement in the electrical conductivity of the composites. The reactive solvent, trifluoroacetic acid, works for the purpose. In addition, the treatment makes a uniform etching in a micro level with little sacrifice in surface roughness of the nanocomposites. The electrical conductivity of 1.0 wt% nanotube composite was enhanced approximately two-fold and three-fold by ten- and thirty-second treatment, which was induced by the reduction in the contact resistance to one half of an original value. It is meaningful that our finding can be an approach to reduce the nanoparticle loading while keeping electrical conductivity in a high level, which can be crucial for securing flexibility or stretchability in a viewpoint that the elongation is inversely proportional to the conductive particle loading. [ABSTRACT FROM AUTHOR]

A technique has been developed utilizing polarized Raman spectroscopy to measure alignment of carbon nanotubes in situ in a polymer matrix under an applied electric field. Previous studies of alignment have been restricted to optically transparent solvents or polymerized specimens that prevent accurate analyses of alignment dynamics in polymers. The effects of electric field strength on the degree of alignment and the time to achieve an aligned state are discussed. The use of in situ , real-time polarized Raman spectroscopy provides a non-invasive technique for assessing carbon nanotube alignment, which can assist in determining processing conditions to improve the mechanical and electrical properties of aligned nanocomposites. [ABSTRACT FROM AUTHOR]

The study of interfacial interactions between polymer matrix and particulate fillers is essential for producing composites with enhanced properties. In this work, the influence of the unique glassy carbon (GC) structure on the properties of its binary epoxy composites as well as hybrid nanocomposites with GC and multi-walled carbon nanotubes (MWCNTs) was investigated. The purpose of incorporating MWCNTs into the epoxy matrix (EP) as an addition filler was to obtain nanocomposites with improved properties. The influence of GC particles alone or in combination with MWCNTs on morphological, thermomechanical, and electrical properties of composites was studied in detail. There were found good, homogeneous dispersion of GC and MWCNTs in epoxy matrix as well as strong interfacial interactions between the carbon fillers and epoxy. Mechanical measurements demonstrated that both the tensile and bending properties of the composites, especially the hybrid composites, were greatly improved compared with those of pure epoxy due to the uniform dispersion of fillers in epoxy and significant adhesion between the filler and matrix. The electrical resistivity of hybrid composites, which is directly related to the presence of MWCNTs in addition to the GC, decreased sharply by 9–11 orders of magnitude compared to the insulating matrix. Such composites with enhanced mechanical and electrical properties could be applied in various branches of industry. [ABSTRACT FROM AUTHOR]

This review mainly concentrates on polyvinyl chloride/carbon nanofiller-based composites. The present study focused upon synthetic strategies and relevance of polyvinyl chloride/graphite, polyvinyl chloride/graphene, polyvinyl chloride/graphene oxide, and polyvinyl chloride/carbon nanotube nanocomposite. Among carbon-based reinforcement, graphene oxide nanofiller depicted better dispersion in polyvinyl chloride matrix. The electrical, mechanical, thermal, and morphological properties of these nanocomposites are also discussed. Moreover, future potential of these materials are elucidated. There is relatively little literature available regarding polyvinyl chloride-based nanocomposite. The main aim of this article is to therefore particularize the polyvinyl chloride-based nanocomposites and expose their concealed properties to enable better use of these new materials in different technical fields. [ABSTRACT FROM PUBLISHER]

In this study, electrical wire explosion has been used to produce aluminum carbon nanotube (Al-CNT) nanocomposite particles in acetone medium. In order to synthesize Al-CNT nanocomposites, initially, CNTs were ultrasonically dispersed. Then, aluminum wire was exploded in this medium. Synthesized samples were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Transmission Electron Microscopy (TEM) methods. The results exhibited formation of spherical nanoparticles in the medium. The average diameter of nanoparticles was 4 nm. Moreover, attained nanoparticles remained stable in acetone. Results revealed a good interaction between aluminum nanoparticles and CNTs in this medium. It is concluded that acetone is a suitable medium for synthesizing Al-CNT nanocomposite as appropriate dispersion of Al-CNT nanoparticles can be achieved in this medium. [ABSTRACT FROM AUTHOR]

Electrospinning is a unique and versatile technique to produce nanofibres; the facility to incorporate fillers has expanded its range of applications. This review gives a brief description of the process and the different polymers employed for obtaining nanofibres. Owing to the ability of fibrillation of polyamides, these polymers have resulted in a wide variety of interesting results obtained when using this technique; therefore these features are summarised. Additionally, because of the feasibility of incorporating carbon nanotubes and graphene in these nanofibres and the growing interest on these nanomaterials, this review focuses in the most common methods employed for their incorporation in electrospun polyamides. Several equipment setups used for the electrospinning of the nanofibres are explained. The outstanding electrical, optical, crystallinity, and mechanical properties obtained by a number of research groups are discussed. The potential applications of the resulting nanocomposites have also been explored. [ABSTRACT FROM AUTHOR]

Conducting polypyrrole (PPy) is an attractive material for supercapacitors with a high specific capacitance and environmental friendliness feature, but it suffers from the limited power density and short cycling life due to the low ionic mobility and mechanic stress resulting from ions in/out solid phase, respectively. Here, we present PPy- p-toluenesulfonate (TOS) and functionalized single-walled carbon nanotube (FSWNT) nanorod-like composites deposited by pulse current method in TOS and FSWNT dispersive solutions, with a diameter of less than 20 nm due to the improved FSWNT concentration near the polymerization interface during pulse-off time. The reduced ion diffusion length and the high diffusion coefficient of PPy-TOS synthesized by pulse current method lead to the nanocomposites with a high specific capacitance of 360 F g at a current loading of 20 A g and an ultrafast charging/discharging capability with a value of 280 F g at even 0.1 s. Moreover, the fine nanostructure, which can accommodate the mechanical stress during charging/discharging process, significantly prolongs the cycling life of the nanocomposites, with its capacitance well maintained of 80 % after 100,000 continuous cycles at a current load of 400 A g. All of these enable the nanocomposites to be excellent active materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

In this work, poly (styrene-b-ethylene-ran-butylene-b-styrene) and carbon nanotube (SEBS/CNT) nanocomposites were prepared by melt compounding for electromagnetic shielding applications. The structural characteristics and the morphology of carbon nanotubes (CNT) and nanocomposites were investigated using Raman spectroscopy and Field Emission Gun Scanning Electron Microscopy. The DC electrical conductivity of the nanocomposites was evaluated by two-probe and four-probe methods, and the electrical percolation threshold was calculated. Dielectrical properties, shielding mechanisms, and the electromagnetic interference shielding effectiveness (EMI-SE) of the nanocomposites were evaluated for the 8.2–12.4 GHz X-band microwave frequency range. A comparison between theoretical and experimental EMI-SE results was also reported. The nanocomposites studied exhibited a very sharp insulator-conductor transition at a CNT concentration of around 1 wt%, and the electrical conductivity increased by 17 orders of magnitude upon addition of more than 2 wt% CNT. Upon addition of 15 wt% of CNT, an EMI-SE of 30.07 dB, which corresponds to a reduction of 99.9% of the incident radiation, was obtained. The results indicate that the nanocomposites studied are promising candidates for electromagnetic shielding applications. [ABSTRACT FROM AUTHOR]

It was found that increase in the content of carbon nanotubes with various chemical structures and geometry in composite materials based on cross-linked polyurethanes leads to increase of the conductivity and tensile strength, accompanied by decrease of their elongation at break. Systems with carbon nanotubes of largest external diameter have the highest conductivity and tensile strength over the whole range of concentrations. It was shown that the presence of nitrogen atoms at the nodes of the nanotubes reduces the conductivity and has little effect on the tensile strength of the polyurethane composites. [ABSTRACT FROM AUTHOR]

Microwave absorbing composites were designed and fabricated by using hybrid carbon based fillers (carbon black (CB) and multi-walled carbon nanotubes (MWCNTs)) as absorbent and phenylethynyl-terminated polyimide as matrix, which have superior mechanical properties and high temperature electromagnetic absorption characteristics. The well dispersion of hybrid fillers enhanced the mechanical properties of the composites due to the particle reinforcement. The complex permittivity increased with the increasing temperature in the X-band frequency from 25 °C to 400 °C. The CB linking the MWCNTs contributed to the absorbing properties. The conductance loss made a major contribution to the loss mechanism at an elevated temperature. When the content of hybrid fillers is 5 wt%, the −10 dB bandwidth is 2.2 GHz and 2.1 GHz with the thickness of 1.7 mm at 25 °C and 200 °C, respectively. Further increasing the temperature would deteriorate the absorbing properties due to the poor impedance matching. [ABSTRACT FROM AUTHOR]

Synthesizing 3D carbon nanotube (CNT) networks with multifunctional characteristics has stimulated the interest from the scientific community since the 1990s. Here, the fabrication of a novel composite material consisting of 3D covalently interconnected multiwalled CNT with silicon carbide (SiC) nano and microparticles is reported. The material is synthesized by a two-step process involving the coating of CNT with silicon oxide (SiO x) via chemical routes, followed by spark plasma sintering (SPS). SPS enables carbothermal reduction of SiOx and subsequent densification of the material into 3D composite blocks. Covalent interconnections of CNT are facilitated by a carbon diffusion process resulting in SiC formation as SiOx coated CNT are subjected to high temperatures. The presence of SiC in the sintered composite has been confirmed by Raman spectroscopy, as well as through energy filtered transmission electron microscopy maps. Interestingly, the 3D CNT composite exhibits high thermal conductivity (16.72 W m−1 K−1); and also a semiconducting behavior with an electron hopping mechanism associated to a 3D variable range hopping model. These findings demonstrate that it is indeed possible to fabricate SiC-CNT composites with enhanced physical properties that can be used as multifunctional materials. [ABSTRACT FROM AUTHOR]

This study is focused on the preparation of electrically conductive nanocomposite adhesives based on epoxy resin or chloroprene rubber containing polyaniline, and multi-walled carbon nanotubes (MWCNTs). For this purpose, MWCNTs were carboxylated (MWCNTs-COOH) by conventional acid oxidation process, and then poly(ethylene glycol) monomethylether was covalently attached to the carboxylated MWCNTs via a esterification reaction. Moreover, carboxylic groups in the MWCNTs-COOH were reduced to alcohol groups (MWCNTs-OH), and then dodecyl-functionalized MWCNTs was synthesized by a substitution nucleophilic reaction in the presence of a solvent composed of 1-bromo dodecane, sodium hydride (NaH), and dry N, N-dimethylformamide (DMF). The functionalized carbon nanotubes (0.5, 1, 1.5, and 2 wt%), and nanopolyaniline (2, 4, 6, 8, and 10 wt%) were added to epoxy resin or chloroprene rubber to produces electrically conductive nanocomposite adhesives. [ABSTRACT FROM AUTHOR]

This study examines the piezoresistive behavior of polyethylene (PE) composites containing different types of carbon nanoparticle fillers. The fillers investigated are single-wall carbon nanotube (SWCNT), multi-wall carbon nanotube (MWCNT), and graphene nanoplatelets (GNP), which were dispersed in PE through melt blending in concentrations ranging between 0.5 and 10 wt%. The dispersion and nanocomposite morphology were investigated using scanning electron microscopy and X-ray diffraction with strong evidence found for shear-induced orientation of GNP nanoparticles during the compression molding process. The conductivity and permittivity of the composite materials was investigated using impedance spectroscopy and the lowest percolation threshold and highest electrical conductivity was observed for SWCNT composites, followed by MWCNT and GNP. The compressive piezoresistance of the nanocomposites was measured and the initial, elastic, and plastic deformation regions were all identifiable by the resistance measurements. The main finding of this study is that the piezoresistance of MWCNT nanocomposites is more sensitive to the effects of varying stress and composition than SWCNT nanocomposites. This indicates an evolving filler network in the case for MWCNT, while a static network for SWCNT, which is explained by the higher aspect ratio and surface area of the latter. POLYM. ENG. SCI., 55:1643-1651, 2015. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This paper reports the preparation and characterization of newly developed conductive nanocomposites consisting of epoxy (EP) and polyaniline-coated halloysite nanotubes (HNT-PANI). The nanocomposites achieved its electrically conductive state (10-5 S·cm-1) and improved impact strength (76 % increase compared to neat EP) with the addition of 12 wt% HNT-PANI. Such mechanically stable conductive nanocomposite could be useful in many applications such as electromagnetic interference shielding and charge dissipating material for secondary load bearing components plus the advantage of being cost effective. [ABSTRACT FROM AUTHOR]

In this work, polymer-based nanocomposite films formed from biphenol poly(arylene ether nitrile) (BP-PEN) and multiwalled carbon nanotubes (MWCNTs) were successfully prepared by the solution casting method combined with continuous ultrasonic dispersion technology. The micromorphology, thermal, mechanical and dielectric properties of the nanocomposite films were investigated in detail. Non-isothermal crystallization behavior studies indicate that the presence of MWCNTs enhances the crystallization of BP-PEN in the nanocomposites, which is consistent with the XRD analysis. Most importantly, it could be observed that the film containing 0.8 wt% MWCNTs reached the maximum crystallinity. Although, incorporation of MWCNTs did not obviously increase the mechanical of the films, all the nanocomposite films still exhibited excellent mechanical strength. The SEM micrographs of the nanocomposite films showed that the MWCNTs were uniformly coated by BP-PEN crystals, and indicating significantly improved nucleation ability of MWCNTs for polymer crystallization. [ABSTRACT FROM AUTHOR]

Carbon nanotubes grafted onto the surfaces of spherical silica gels were incorporated into epoxy polymer to yield nanocomposite. The efficiency of this approach in controlling the dispersion of carbon nanotubes within the epoxy matrices was observed from the scanning electron microscope images, where the nanotubes remained strongly attached to the surface of the gel. As the micron-sized silica introduced a large excluded volume within the polymer matrices, the nanotubes dispersion remained restricted to a region along the silica surface and bundle formation was prevented. This arrangement aided the formation of an electrically conductive network in an epoxy matrix, where the critical percolation threshold (pc) was calculated as pc = 0.5 wt., which is equivalent to 0.16 wt. % nanotubes, as previously determined from thermal gravimetric analysis. The equivalent circuit model to represent the electrical properties was proposed to analyse the interactions between the real impedance (Z') and imaginary impedance (Z'') components of the hybrid nanocomposites. The two parallel RC circuits were found to fit the data well, describing the interaction between epoxy and conductive silica-- nanotubes hybrid. [ABSTRACT FROM AUTHOR]

ABSTRACT In order to develop new electronic devices, it is necessary to find innovative solutions to the eco-sustainability problem of materials as substrates for circuits. We realized a photoresponsive device consisting of a semiconducting polymer film deposited onto optically semitransparent and conductive biodegradable poly(3-hydroxybutyrate) (PHB)/carbon nanotube (CNT) substrates. The experiments indicated that the PHB-CNT bionanocomposite substrate behaves as an optical window trapping electric charges produced by the photoexcitation of the semiconducting polymer. Such PHB-CNT functional substrates are expected to be attractive for eco-friendly electronics. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 596-602 [ABSTRACT FROM AUTHOR]

Abstract: The last decade has seen a growing interest in hybrid electrically conducting nanocomposites. This article aims to provide a detailed overview of the present status of research in carbon nanotube–polyaniline (CNT/PANI) composites, from processing to structural and property evaluations. CNT/PANI are synthesized by electrochemical and chemical processing. When chemical methods are used, the main challenge is to obtain processable CNT/PANI in the emeraldine salt (ES) form composites. Stable dispersions of ES–CNT in organic media are prepared using the post doping method, inverse emulsion polymerization, or ex situ polymerizations. On the contrary, stable water dispersions of CNT/ES are prepared using hydrophilization of a preformed CNT/ES composite, direct synthesis of micelle–CNT hybrid templates, interfacial polymerization, covalent functionalization of CNT with a water soluble polymer, or using electrostatic interactions between two oppositely charged ES and CNT aqueous colloids. Moreover, the strategies for the synthesis of ternary CNT/PANI composites incorporating noble metal nanoparticles, metal oxide, or graphene sheets are also presented and analyzed in depth. Finally, we give a review of potential applications, including chemical sensors, capacitors, fuel cells and electronic devices. [Copyright &y& Elsevier]

Carbon nanotube (CNT)/ultrahigh-molecular weight polyethylene (UHMWPE) nanocomposite with an electrical percolation threshold of only 0.1 wt% was prepared by simple dry mixing followed by compression molding. The nanocomposite microstructure, direct current and alternating current (AC) electrical conductivities, conduction mechanisms, and dielectric properties in the 101–105 Hz frequency range have been investigated. Due to the localization of the nanofiller at the surface of UHMWPE powder particles, a segregated microstructure within the polymer matrix was created. Nanocomposites filled with 0.125–0.5 wt% CNT were found to follow the typical universal dynamic response behavior, and the characteristic frequency was found to increase with the increase in CNT concentration. At CNT concentration ≥ 0.5 wt%, the AC conductivity was found to be frequency independent over the entire frequency range studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examine the mechanical/electrical properties of geopolymers containing MWCNTs. [•] Excellent mechanical and electrical properties at 0.1 and 0.5% MWCNTs. [•] Good dispersion of MWCTs at 0.1 and 0.5% and agglomeration at 1% MWCNTs. [•] Piezoresistive response with high sensitivity to crack propagation. [Copyright &y& Elsevier]

ABSTRACT The influence of injection molding parameters on electrical properties and morphology of PC/ABS-MWCNT nanocomposites is presented in this article. Investigation is based on the masterbatch of 5.0 wt % carbon nanotubes obtained by melt-mixing. Further processing includes dilution of this nanocomposite to desired concentrations on twin-screw extruder and injection molding or direct dilution of masterbatch in injection molding. Additionally, reprocessing of materials formed by compression and injection molding is presented along with the change in electrical conductivity. Morphology differs strongly between the two processing paths showing change in agglomeration behavior between nanotubes concentrations. Electrical properties show dependence on injection velocity and melt temperature in both applied processing paths. Moreover, electrical conductivity recovery is proved after injection and compression molding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2152-2158, 2013 [ABSTRACT FROM AUTHOR]

Electrically conducting nanocomposites of polyaniline (PANI) with carbon-based fillers have evinced considerable interest for various applications such as rechargeable batteries, microelectronics, sensors, electrochromic displays and light-emitting and photovoltaic devices. The nature of both the carbon filler and the dopant acid can significantly influence the conductivity of these nanocomposites. This paper describes the effects of carbon fillers like carbon black (CB), graphite (GR) and muti-walled carbon nanotubes (MWCNT) and of dopant acids like methane sulfonic acid (MSA), camphor sulfonic acid (CSA), hydrochloric acid (HCl) and sulfuric acid (HSO) on the electrical conductivity of PANI. The morphological, structural and electrical properties of neat PANI and carbon-PANI nanocomposites were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and the four-point probe technique, respectively. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) studies were also conducted for different PANI composites. The results show that PANI and carbon-PANI composites with organic acid dopants show good thermal stability and higher electrical conductivity than those with inorganic acid dopants. Also, carbon-PANI composites generally show higher electrical conductivity than neat PANI, with highest conductivities for PANI-CNT composites. Thus, in essence, PANI-CNT composites prepared using organic acid dopants are most suitable for conducting applications. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotubes grown on clay platelets (Clay-CNTs hybrids) were incorporated into a poly(l-lactide) (PLLA) matrix through high energy ball milling at ambient temperature. Carbon content was varied from 0.60 to 5wt%. Crude carbon nanotubes (CNTs), after purification from the clay, were also incorporated into PLLA in the same conditions and amount. Thin films were obtained on laboratory scale. Electrical behaviour was analysed on all nanocomposites. CNTs grown on the clay platelets showed a better dispersion into the polymer matrix than the crude ones, as evidenced in a significant decreasing of percolation threshold. I–V characteristics were also dependent on the morphology of the filler. [Copyright &y& Elsevier]

Preparation and analysis of morphology, mechanical, and electrical properties of nanocomposites based on ethylene vinyl acetate (EVA) copolymer and commercial multiwalled carbon nanotubes (CNTs) was achieved. The used techniques for obtaining nanocomposites were the conventional melt-mixing and the in situ ethylene polymerization/coating reaction, as catalyzed directly from CNT surface, with different polyethylene content (i.e. 55.0% and 66.6%). Nanocomposites were also prepared using crude CNTs. The incorporation in the molten state of such polyethylene surface-coated CNTs, used as 'masterbatch,' in EVA was demonstrated a good strategy for allowing the complete destructuring of the native bundle-like aggregates, leading to the preparation of polymer nanocomposites with largely improved properties, even at very low nanofiller content. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A structure aimed at modeling a polymeric nanocomposite loaded with carbon nanotubes (CNTs) is simulated by considering, in a three-dimensional space, a random distribution of impenetrable conducting cylinders inside an insulating cubic matrix. The variation of the electrical conductivity of the structure for different volume loadings of the conducting phase is estimated through a 3D resistor network. The tunneling effect between conducting clusters which is deemed responsible of the global conductivity is taken into account. By using a Monte Carlo method, the electrical conductivity and the percolation thresholds of the obtained structures are analyzed as a function of geometrical and physical influencing parameters. [ABSTRACT FROM AUTHOR]

Composites from polystyrene and multi-walled carbon nanotubes (CNTs) were prepared by a forge-rolling method. The predominant CNT alignment with the rolling direction was deduced from measurements of filler content dependence on the composite permittivity. A simple method of CNT reorientation in polymer matrix was developed, and it was shown that the effective longitudinal polarizability of nanotubes in the samples obtained is ˜5 times larger than the transverse one. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotubes (CNTs)–polyacrylic acid (PAA) composite film has been successfully fabricated by electrophoretic deposition method in PAA aqueous solution containing CNTs and used as electrodes for capacitive deionization (CDI). The PAA serves as the cation-exchange polymer and the matrix to incorporate the CNTs. The CDI unit cell based on CNTs–PAA composite film electrode exhibits a high NaCl removal of 83%, 51% higher than that of the cell based on pure CNTs electrode, with a good regeneration ability. [Copyright &y& Elsevier]

Abstract: Composites of MWCNTs having each three different levels of matrix viscosity with five different polymers (polyamide 12, polybutylene terephthalate, polycarbonate, polyetheretherketone and low density polyethylene) were melt mixed to identify the general influence of matrix viscosity on the electrical properties and the state of MWCNT dispersion. Huge differences in the electrical percolation thresholds were found using the same polymer matrix with different viscosity grades. The lowest percolation thresholds were always found in the composites based on the low viscosity matrix. The state of primary MWCNT agglomerate dispersion increased with increasing matrix viscosity due to the higher input of mixing energy. TEM investigations showed nanoagglomerated structures in the low viscosity samples which are obviously needed to achieve low resistivity values. The effect of nanotube shortening was quantified using two different viscosity grades of polycarbonate. Due to the higher mixing energy input the nanotube shortening was more pronounced in the high viscosity matrix which partially explains the higher percolation threshold. [Copyright &y& Elsevier]

Abstract: A comparative study of the influence of processing route on polyurethanes (PUs)/multiwalled carbon nanotube (MWCNT) composites mechanical and electrical properties and also morphology was undergone employing two differentiated processing methods, solvent casting and buckypaper infiltration, for producing PU composites with low, medium and high mass fractions of acid treated MWCNT, and with no covalent linkages between the matrix and the nanotubes. As for example, with a MWCNT mass fraction of ∼18wt.% the second method produced stiffer (270MPa), lighter (948kgm−3) and more electrically conductive (1.8Scm−1) composite while the first one gave softer (111MPa) and more ductile (141%) materials. These properties differences are related to the different PU/MWCNT dispositions obtained through each synthesis route. Nanotubes percolating concentration is found to be crucial on composite properties evolution and a preferential interaction of MWCNT with PU hard segments is observed for solvent cast composites. [Copyright &y& Elsevier]

As a type of thin film, two dimensional (2D) reticulate architectures built of freestanding single-walled carbon nanotube (SWCNT) bundles are suitable for scalable integration into devices and nanocomposites for many applications. The superior properties of these films, such as optical transparency, unique electrical properties and mechanical flexibility, result not only from the outstanding properties of individual SWCNTs but also from the collective behavior of the individual tubes, with additional properties arising from the tube-tube interactions. In this review, the synthesis, structure and fundamental properties, such as conductivity, transparency, optical nonlinearity and mechanical performance, of 'freestanding SWCNT bundle network' thin films and nanocomposites, as well as their application as supercapacitors are highlighted. Some long-standing problems and topics warranting further investigation in the near future are addressed. [ABSTRACT FROM AUTHOR]

Abstract: Multi-walled carbon nanotube (MWCNT)/MnO2 supercapacitor electrodes containing MnO2 nanoflakes in the MWCNT network are fabricated through the oxidation of manganese acetate with poly(4-styrenesulfonic acid) (PSS) dispersed MWCNTs. The structural evolution of the electrodes under charge/discharge (reduction/oxidation) cycles and its impact on the electrodes’ electrochemical properties are evaluated. Structural evolution involves the dissolution of MnO2 upon reduction, the diffusion of the reduced Mn species from the MWCNT network toward the electrolyte solution, and the deposition of MnO2 on the electrode surface upon oxidation. Electrode structural changes, including the electrode dissolution and the growth of the MnO2 crystals, are scan rate dependent and have deteriorating effect on the electrode''s electrochemical properties including the specific capacitance and cyclic stability. [Copyright &y& Elsevier]

Abstract: Graphene, whose structure consists of a single layer of sp2-hybridized carbon atoms, provides an excellent platform for designing composite nanomaterials. In this study, we have demonstrated a facile process to synthesize graphene–multiwalled carbon nanotube (MWCNT) composite. The graphene–MWCNT composite material is endowed with a large electrochemical surface area and fast electron transfer properties in Fe(CN)6 3−/4− redox species. A graphene–MWCNT composite modified electrode exhibits good performance in terms of the electrocatalytic reduction of H2O2; a sensor constructed from such an electrode shows a good linear dependence on H2O2 concentration in the range of 2×10−5 to 2.1×10−3 molL−1. The detection limit is estimated to be 9.4×10−6 molL−1. This study provides a new kind of composite modified electrode for electrochemical sensors. [Copyright &y& Elsevier]

Nanocomposites have unprecedented potential for conductivity-based damage identification when used as matrices in structural composites. Recent research has investigated nanofiller alignment in structural composites, but because damage identification often requires in-plane measurements, percolation and conductivity transverse to the alignment direction become crucial considerations. We herein contribute indispensable guidance to the development of nanocomposites with aligned nanofiller networks and insights into percolation trends transverse to the alignment direction by studying the influence of alignment on transverse critical volume fraction, conductivity, and rate of transition from non-percolating to percolating in three-dimensional carbon nanotube composite systems. [ABSTRACT FROM AUTHOR]